1. Field of the Invention
The present invention relates to the control and calibration of an automated master friction clutch as utilized in an at least partially automated mechanical transmission system.
2. Description of the Related Art
Vehicular automated mechanical transmission systems comprising a multiple-speed mechanical transmission drivingly connected to a fuel-controlled engine by means of an automatically actuated vehicle master friction clutch are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,081,065; 4,361,060; 4,527,447; 4,638,898; 4,648,290; 4,714,144; 4,873,637; 5,275,267; 5,293,316; 5,314,050 and 5,316,116, the disclosures of which are incorporated herein by reference.
To improve the controllability and responsiveness of the prior art master clutch control systems, it was known to determine a clutch control parameter value, such as a clutch actuator position, which corresponded to the "touch point" or "point of incipient engagement" of the clutch, i.e., that point or position during engagement of the master clutch at which the master clutch just began to transmit torque. The clutch touch point was determined or calibrated during a system startup routine and was thereafter subject to updating during ongoing vehicle operations.
During a controlled master clutch engagement, the master clutch was moved rapidly from its disengaged position to the touch point/point of incipient engagement, and then was further engaged in a controlled, modulated manner according to the applicable clutch control logic. Examples of such clutch control logic may be seen by reference to U.S. Pat. Nos. 4,646,891; 4,899,858 and 5,337,874, the disclosures of which are incorporated herein by reference.